The Thyroid Cascade – Why Do I Still Have Thyroid Symptoms?

Thyroid function is surprisingly complex, with hormones changing into other hormones, organs affecting other organs and the brain controlling it all. Because of this, effective treatment for thyroid imbalances just isn’t as simple as prescribing synthetic thyroid hormone and hoping for the best. More often than not, the standard medical approach is surprisingly ineffective after just a short time, leading to a slow (or fast) return of fatigue, hair loss and weight gain. My practice is filled with people who have the same symptoms before and after being treated this way.

Let’s take a patient at our clinic, Betsy, who didn’t suffer any symptoms of low thyroid whatsoever until she became pregnant five years ago. She then developed all the symptoms mentioned above, plus cold hands and severe constipation. After a confusing time with her doctors, who diagnosed her with depression, it was finally found that she had low thyroid function. She was put on Synthroid (levothyroxin) and felt a bit better, but only for about two months. Slowly all her symptoms returned, became much worse, and she had the additional problems of brain fog and insomnia. When I first saw her, she was so fatigued and un-functional that she thought she might lose her family, job and mind if something wasn’t done.

Our work up showed that her thyroid was functioning below par, in spite of taking prescription thyroid hormones. This was because of an under-conversion of T4 (thyroid hormone) to T3, the active form of the hormone that does all the work of increasing cell function, preventing fatigue and elevating mood. We then set to work correcting the problems she had with this T4 to T3 conversion. Using targeted supplements and a dietary change to decrease inflammation and alter the bacterial balance in her GI tract (the place where conversion happens) resolved her fatigue, brain fog and insomnia.

It is unfortunately very common that doctors (including most endocrinologists) don’t fully test all the indicators of possible thyroid problems. It turns out that there is a Thyroid Cascade–a series of steps–that must take place in order to synthesize thyroid hormone, and have it work affectively. These steps are listed below.

The 8 Steps of the Thyroid Cascade

1)      The brain (hypothalamus), realizing a need for thyroid hormone, sends messages to the pituitary gland.

2)      The pituitary gland sends a message to the thyroid to produce more hormone.

3)      The thyroid stimulates TPO to transport iodine to the thyroid.

4)      This leads to the production of T4 and T3.

5)      These hormones are then bound to protein (Thyroid Binding Globulin).

6)      The T4 is changed to a combination of T3 hormones in the liver.

7)      The gut bacteria change the inactive T3 hormones to active hormones.

8)      The unbound T3 hormones bind to the receptors of the target cells.

I won’t be able to describe the steps in detail in the space allotted, but the important take-away message here is that any of the eight steps of the cascade can bog down, leading to low thyroid output and that is why taking thyroid hormone (only step 4) usually doesn’t work. Betsy’s problem was with step seven, and if this wasn’t rectified, her condition would continue to degrade.

Each of these steps must be considered to fully understand the CAUSE of thyroid dysfunction, and this doesn’t even get close to addressing the important relationships with adrenal gland, glucose regulation, immune problems and gut function that can cause very similar symptoms. That’s why a comprehensive evaluation with very specific and comprehensive lab testing is required to discover the step or steps that are problems, and to outline your unique bio-individuality in order to fully understand the actual cause of your symptoms. The results can be long lasting and life changing. That’s what happened to Betsy, and hundreds of others who were willing to take the next step to wellness.

Dr. Don Davis, D.C., DACNB is a BOARD CERTIFIED CHIROPRACTIC NEUROLOGIST in Walnut Creek. He has been serving individuals with chronic pain for 30 years. For information about how you can get a free consultation with Dr. Davis, call (925) 279-4324 (HEAL). Visit us at